Only allow installation of extensions/apps with gallery update url via download from gallery

chrome/common/extensions/extension_constants.h

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
 
 // Keys used in JSON representation of extensions.
 namespace extension_manifest_keys {
   extern const wchar_t* kAllFrames;
@@ skipping 154 matching lines @@
   extern const char* kInvalidOmniboxKeyword;
   extern const char* kOmniboxExperimental;
 }  // namespace extension_manifest_errors
 
 namespace extension_urls {
   // The greatest common prefixes of the main extensions gallery's browse and
   // download URLs.
   extern const char* kGalleryBrowsePrefix;
   extern const char* kGalleryDownloadPrefix;
 
+  // The update url used by gallery/webstore extensions.
+  extern const char* kGalleryUpdateURL;
+
   // Same thing for the "minigallery". The minigallery is the temporary static
   // themes gallery that we put up when we launched themes.
   extern const char* kMiniGalleryBrowsePrefix;
   extern const char* kMiniGalleryDownloadPrefix;
 }  // namespace extension_urls
 
 namespace extension_filenames {
   // The name of a temporary directory to install an extension into for
   // validation before finalizing install.
   extern const char* kTempExtensionName;
 
   // The file to write our decoded images to, relative to the extension_path.
   extern const char* kDecodedImagesFilename;
 
   // The file to write our decoded message catalogs to, relative to the
   // extension_path.
   extern const char* kDecodedMessageCatalogsFilename;
 }
 
 namespace extension_misc {
   const int kUnknownWindowId = -1;
 }  // extension_misc
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_